Reinforcing bar



March 10, 1964 E. J. VAN KOOT REINFQRCING BAR Filed Jan. 19, 1961 Fig. l

INVENTOR Fduard Jan van Koat Afr/S.

United States Patent 3,123,941 REIINFORCING BAR Eduard Jean van Koot, Doorwerth, Netherlands, assignor to Tor-isteg Steel Corporation S.A.H., Luxembourg Filed Jan. 19, 1%1, Ser. No. 83,720 Claims priority, application Germany Jan. 20, 1960 1 Claim. (Cl. 50-527) This invention relates to a reinforcing bar, more particulanly a reinforcing bar for use in concrete, which is provided on the surface of its preferably cylindrical oar core with a plurality of individual oblique lugs or short ribs which are inclined relatively to the bar axis and which, arranged individually in specific directions, have a uniform cross-section over substantially their entire length.

Many constructional forms of such reinforcing bars are known; in some cases these bars are also provided with longitudinal ribs, and in some cases no such longitudinal ribs are provided and then only oblique lugs or ribs are arranged on the bars.

The first-mentioned bars with longitudinal ribs in some cases exhibit less flexibility than smooth bars, and in fact this has been found to be due to the peak stresses occurring at the apices of the longitudinal ribs. If the longitudinal ribs are provided with sharp edges, the fatigue strength of the bar is also reduced.

If no longitudinal ribs are provided, and the bars only comprise oblique lugs or ribs all inclined in the same direction, there is a danger that when the bar embedded in concrete is subjected to stress it may rotate out of its bond, particularly if the bar was subjected to a quality-improvement treatment by twisting. Bars are in fact already known in which this risk has been countered by arranging inclined lugs in various directions of inclination, namely, inclined in opposite directions to one another. But this results in the disadvantage that when such bars are twisted, some of the lugs are upset and others are stretched. Now, the upsetting or stretching of such lugs can lead to various disadvantageous effects depending on the quality of steel and on the kind of quality-improving treatment to be carried out, after-treatment, aging, etc., and may particularly result in rendering the bar brittle with peak stresses at the lug apices, and further undesirable effects.

It has already been recognized in connection with this that it is more advantageous to arrange the oblique lugs of a bar in the same direction of inclination throughout, so that when such a bar is twisted, either all the lugs are upset or all are stretched.

The invention relates to a reinforcing bar having a plurality of individually arranged oblique lugs or short ribs of substantially uniform cross-section, which are inclined relatively to the bar axis. It is characterized in that the individual oblique lugs are directed at different acute angles to the bar axis. Preferably, the oblique lugs can form with the bar axis angles in the range of between and 80.

Bars are in fact already known in which short lugs are arranged between longitudinal ribs and deviate from a line parallel to the course of the longitudinal ribs first in one direction and then in the other.

In contrast, the invention is concerned with the arrangement on the bar periphery of only' oblique :lugs or short ribs which are arranged individually and which form 3,123,941 Patented Mar. 10, 196 1 'ice different acute angles among themselves with the bar axis. The fact that longitudinal ribs are not provided facilitates the rolling of the steel and avoids the initially mentioned dangerous disadvantages which result from the provision of longitudinal ribs.

The invention can be put into effect in various ways. For example, according to a further important feature of the invention, the oblique lugs can be arranged in groups identical to one another, the lugs within each group being always arranged at different angles relatively to the bar axis; for example, lugs arranged at different angles from one another can alternate with one another in each individual group.

It is also possible Within the scope of the invention for the oblique lugs to be arranged in at least two groups which are not similar to one another, the lugs within each group being preferably parallel to one another, but extending at different angles to the bar axis from those formed by the other group or groups.

For the quality improvement of a bar according to the invention by cold working, this bar can be twisted either in the direction of inclination of the oblique lugs or in the direction opposite thereto. Which of these methods is to be preferred in each individual case depends more particularly on the kind of quality-improvement treatment and after-treatment of the bar, andas initially mentionedit must be borne in mind that the lugs are subjected to either an upsetting eifect or a stretching effect during twisting.

Two forms of the invention are illustrated in the drawings, in which:

FIG. 1 is a side elevational view of a part of a reinforcing bar of cylindrical formation with the lugs at one side of the bar being of different lengths and alternate lugs extending at the same angle to the longitudinal axis of the bar and mating with similar lugs at the opposite side of the bar, and

FIG. 2 is a view similar to FIG. 1, wherein the lugs at each side of the bar are parallel and the lugs at one side of the bar are longer than the other side lugs and extend at more acute angles to the longitudinal axis of the bar.

The cylindrical bar core is designated in each case by the reference numeral '1, and is provided at its surface with diagrammatically indicated oblique lugs 2 which can be of any desired shape in cross-section.

According to FIG. 1, the bar 1 comprises identical groups of oblique lugs 2. and 3' at two opposite sides, and within each group the oblique lugs 2 and 3 are arranged at different angles alternately, e.g. approximately 25 and 45 respectively.

On the other hand, the bar illustrated in FIG. 2 is provided with dissimilar groups of oblique lugs 4 and 5, the side nearest the viewer comprising a group of oblique lugs 4 which are all inclined at 45", whereas the oblique lugs 5 at the rear side are inclined at about 25 relatively to the bar axis 6.

In both cases, the bar is locked against any possibility of rotating out of the concrete, without having to provide for this purpose the longitudinal ribs which are recognized to be inexpedient.

Of course, in addition to the two forms illustrated, many other possibilities are open. More particularly, any desired number of groups of oblique lugs can be provided, and the individual shape of these lugs, their spacing and their length can all be varied optionally within the framework of what is technically possible and the effects which are to be achieved.

What is claimed is:

A reinforcing metal member for concrete comprising a longitudinal cylindrical bar, a set of relatively short oblique lugs on the bar at each of two opposite sides only, each of said lugs being inclined relative to the longitudinal axis of the bar with the ends of each lug of one set being spaced from the ends of the lugs of the other set, said lugs of each set alternately varying in length and in the acute angle defined with the longitudinal axis of the bar, the corresponding ends of the inclined lugs of one set being directed towards a first end of the bar, the corresponding ends of the lugs of the other set adjacent to and spaced from said first named corresponding ends being directed towards the other end of the bar, the spaces between the ends of the lugs of the two sets defining continuous longitudinal unobstructed areas.

References Cited in the file of this patent UNITED STATES PATENTS 

